Solid Catalysts For The Catalytic Oxidation Of Gaseous Cyclohexane

Impregnation method was employed to prepare for carrier-supporting transition metal oxidation solid samples (V-Cu-Zn-K) as hetergenous catalysts in the paper. In the bed-secured micro-reactor and on normal pressure gas-state cyclohexane could be transformed into some partly oxidized products in a given reaction condition.Custom gas chromatogram and GC-MS analysis were adopted to analyze and determine the products. The characteristic of the product distribution and the prosperities of the catalysts revealed that free-radical mechanism might better explain the part oxidation of cyclohexane. Different probable routes were proposed to explain why different oxygenates were deduced from cyclohexane. Meanwhile,analysis was given with respect to the makeup and characteristics of active groups in catalysts suitable to different reaction routes.From the results of activation evaluation experiments,it was found that many factors might be responsible for the makeup and prosperities of the supporting transition metal oxide as heterogenous catalysts. These factors consisted of the makeup and composition of the carrier,method of pre-treatment of the carrier,the type and content involved in alkali metal elements carried and some external reaction conditions such as temperature and flow rate of oxygen.IR spectral helped to analyze how different factors had their effects on the makeup and prosperities of active groups to fit with different reaction routes,to accelerate transformation of cyclohexane and to increase the volume of desired products.Impregnation & drying method was used preparing for catalysts (V2O5/SiO2,P-K-V/SiO2,Cr-K-V/SiO2,Mo-K-V/SiO2 and Fe-K-V/SiO2) which was applied on catalytic cracking-oxidation of cyclohexane. Investigation was also made into the effects of reaction conditions on the supporting catalysts. It was known that some additives on catalyst (V2O5/SiO2) could improve its characteristics of dehydrogenating centers and centers of oxidation greatly and prevent the extended cracking - oxidation of cyclohexane. The surface of the catalysts(Cr-K-V-SiO2 and Fe-K-V-SiO2) possessed active groups with comparably strong dehydrogenting centers and less active centersof oxidation which facilitated the partly cracking-oxidation of cyclohexane.